An algorithm is quickly scans a digital image volume to detect density nodules.
A first stage is based on a transform to quickly highlight regions requiring further
processing. The first stage operates with somewhat lower sensitivity than is possible
with more detailed analyses, but operates to highlight regions for further analysis
and processing. The transform dynamically adapts to various nodule sizes through
the use of radial zones. A second stage uses a detailed gradient distribution analysis
that only operates on voxels that pass a threshold of the first stage.
